The leukotrienes constitute a group of locally acting hormones, produced in living systems from arachidonic acid. The major leukotrienes areLeukotriene B.sub.4 (abbreviated at LTB.sub.4), LTC.sub.4, LTD.sub.4 and LTE.sub.4. The biosynthesis of these leukotrienes begins with the action of the enzyme 5-lipoxygenase on arachidonic acid to produce the epoxide known as Leuukotriene A.sub.4 (LTA.sub.4), which is converted to the other leukotrienes by subsequent enzymatic steps. Further details of the biosynthesis as well as the metabolism of the leukotrienes are to be found in the book Leukotrienes and Lipoxygenases, ed. J. Rokach, Elsevier, Amsterdam (1989). The actions of the leukotrienes in living systems and their contribution to various diseases states are also discussed in the book by Rokach.
Structures A, B and C are representative of benzoheterocyclic hydroxylamine derivatives which are described in the prior art, and which have activity as inhibitors of the 5-lipoxygenase enzyme, which results in inhibition of the synthesis of the leukotrienes. The compounds of the present invention, pyrrolo[1,2a]indole hydroxylamine derivatives are novel in that hydroxylamine derivatives of the parent ring system, 1H-2,3-dihydropyrrolo[1,2-a]indole, are unknown in the prior art, representative of which are the following: ##STR2##